President Obama, addressing yet another memorial gathering after a deadly mass shooting, said Sunday evening that he senses “a creeping resignation” in the United States that homicidal lunacy like the Washington Navy Yard massacre “is somehow the new normal.” But he said “it ought to be a shock to us all” and should spur Americans to demand “a common sense” balance between gun rights and gun control.

“We cannot accept this,” Obama said of the Sept. 16 attack that killed a dozen people at the Navy Yard. “As Americans bound in grief and love, we must insist here today there’s nothing normal about innocent men and women being gunned down where they work.”

Obama was addressing about 4,000 people, including loved ones of the slain, who gathered outdoors at the Marine Corps Barracks at Eighth and I streets SE, a few blocks from the Navy Yard. The president did not vow to throw the weight of his presidency behind an effort to enact gun-control legislation, as he did in December at a memorial service after the slaughter at Sandy Hook Elementary School in Newtown, Conn. Instead, he urged the nation to demand such measures.

“By now . . . it should be clear that the change we need will not come from Washington, even when tragedy strikes Washington,” he said at Sunday’s service on the barracks parade grounds. “Change will come the only way it ever has come, and that’s from the American people.”

The Navy Yard gunman, 34-year-old Aaron Alexis, a former Navy reservist with a recent history of mental problems, opened fire in Building 197, first with a shotgun, then with a pistol, killing nine men and three women. All the victims worked in the building, which houses the Naval Sea Systems Command.

“Part of what wears on . . . is the sense that this has happened before,” the president said. “What wears on us, what troubles us so deeply, as we gather here today is this senseless violence that took place in the Navy Yard echoes other recent tragedies.”

And he intoned the names of the places he has visited as president in the wake of mass homicides: Fort Hood, Tex.; Tucson; Aurora, Colo., and Newtown. “Once more our hearts are broken,” he said. “Once more we ask why.”

Joined on stage by Defense Secretary Chuck Hagel, Navy Secretary Ray Mabus, D.C. Mayor Vincent C. Gray (D) and other dignitaries, Obama shared personal details about each of the Navy Yard victims, saying: “These are not statistics. They are the lives that have been taken from us. This is how a single act of violence can ripple.

“A husband lost his wife. Wives have lost their husbands. Sons and daughters have lost their moms and their dads. Little children have lost their grandparents. Hundreds in our communities have lost a neighbor. And thousands here have lost a friend.”

Echoing Obama, Gray told the gathering that “our country is drowning in a sea of guns. . . . Senseless violence like this is an all-too-everyday fact of life here in the District and in our nation’s other big cities. It is a fact of life that we must stop accepting.”

As he did Saturday night in an address to the Congressional Black Caucus, Obama spoke in a tone of frustration about the political stalemate that derailed his push for gun-control legislation after the Sandy Hook massacre. In the spring, lawmakers who had long pushed for expanding background checks on gun buyers and reinstating the ban on assault weapons thought that the time for action was ripe after 20 children and six adults were slain in Newtown. But the efforts failed in Congress.

“The politics are difficult, as we saw again this spring,” Obama said. “And that’s sometimes where the resignation comes from — the sense that our politics are frozen and that nothing will change.”

Looking at the loved ones of the Navy Yard victims, Obama said: “These families have endured a shattering tragedy. It ought to be a shock to us all. It ought to obsess us. It ought to lead to some sort of transformation.”

He spoke of mass shootings in the United Kingdom and Australia, saying that people in those nations responded by enacting gun limitations, as they “understood that there was nothing ordinary about this kind of carnage. They endured great heartbreak, but they also mobilized and they changed. And mass shootings became a great rarity.”

Yet in the United States, “after all the speeches and all the punditry and all the commentary, nothing happens. Alongside the anguish of these American families, alongside the accumulated outrage so many of us feel, sometimes I fear there’s a creeping resignation, that these tragedies are just somehow the way it is.”

He said: “No other advanced nation endures this kind of violence. None. Here in America, the murder rate is three times what it is in other developed nations. The murder rate with guns is 10 times what it is in other developed nations. And there’s nothing inevitable about it. It comes about because of decisions we make or fail to make. . . .

“I do not accept that we cannot find a common sense way to preserve our traditions, including our basic Second Amendment freedoms and the rights of law-abiding gun owners while at the same time reducing the gun violence that unleashed so much mayhem on a regular basis.”

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